[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-seo-648223-105":3,"detail-sidebar-cat-0-en-105":80,"doc-detail-648223-en":130},{"code":4,"msg":5,"data":6},0,"ok",{"site_id":7,"language":8,"slug":9,"title":10,"keywords":11,"description":12,"schema_data":13,"social_meta":73,"head_meta":75,"extra_data":77,"updated_unix":79},105,"en","drm11thsect21","DRM11thSECT21","","Section 21 outlines the purpose and scope for drafting and dimensioning practices used when preparing drawings for sheet-metal parts to be fabricated. It references applicable engineering drawing standards, including ASME Y14 practices and MIL standards for fasteners and rivet/screw installation. The section defines key sheet-metal terminology such as bend allowance, bend angle, bend line, bend radius, bend relief, bevel configurations, blank, center line of bend, developed length, dimpling, and related molding and pattern concepts used in dimensional calculations.",{"@graph":14,"@context":72},[15,34,55],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/research-report/","Research & Report",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/drm11thsect21/648223/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/drm11thsect21/648223.png","ImageObject",300,407,{"name":42,"@type":43},"8796093062539","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-10-26","2026-10-23",true,{"@type":52,"interactionType":53,"userInteractionCount":26},"InteractionCounter",{"@type":54},"ViewAction",{"@type":56,"mainEntity":57},"FAQPage",[58,64,68],{"name":59,"@type":60,"acceptedAnswer":61},"What is the purpose of Section 21 (21.1.1)?","Question",{"text":62,"@type":63},"It establishes drafting and dimensioning practices for preparing drawings for sheet-metal parts, helping draftsmen set proper dimensions for features of formed parts.","Answer",{"name":65,"@type":60,"acceptedAnswer":66},"Which standards and documents are referenced as applicable (21.2)?",{"text":67,"@type":63},"The section cites ASME Y14.100 and ASME Y14.5M drawing practices, along with MIL-STD-403 for rivets and screws and NAS 523 fastener code for aerospace, plus a DoD policy memo affecting waiver requirements.",{"name":69,"@type":60,"acceptedAnswer":70},"How is the median line (neutral axis) used in bend allowance calculations (21.5.1 and 21.3.16)?",{"text":71,"@type":63},"It represents the line within the bend where no stretching or compression occurs, and it is located approximately 44% of the material thickness from the inside surface of the bend; it forms the basis for bend allowance calculations.","https://schema.org",{"og:url":32,"og:type":74,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":76,"canonical":32},"index,follow",{"doc_id":78,"site_id":7},648223,1792974744,{"code":4,"msg":81,"data":82},"success",[83,87,91,95,100,105,110,114,119,122,126],{"id":22,"doc_module":4,"doc_module_name":25,"category_name":84,"show_sort_weight":85,"slug":86},"Story & Novel",90,"story-novel",{"id":26,"doc_module":4,"doc_module_name":25,"category_name":88,"show_sort_weight":89,"slug":90},"Literature",80,"literature",{"id":33,"doc_module":4,"doc_module_name":25,"category_name":92,"show_sort_weight":93,"slug":94},"Exam",70,"exam",{"id":96,"doc_module":4,"doc_module_name":25,"category_name":97,"show_sort_weight":98,"slug":99},5,"Comic",60,"comic",{"id":101,"doc_module":4,"doc_module_name":25,"category_name":102,"show_sort_weight":103,"slug":104},6,"Technology",50,"technology",{"id":106,"doc_module":4,"doc_module_name":25,"category_name":107,"show_sort_weight":108,"slug":109},7,"Healthcare",40,"healthcare",{"id":111,"doc_module":4,"doc_module_name":25,"category_name":29,"show_sort_weight":112,"slug":113},8,30,"research-report",{"id":115,"doc_module":4,"doc_module_name":25,"category_name":116,"show_sort_weight":117,"slug":118},9,"Religion & Spirituality",20,"religion-spirituality",{"id":117,"doc_module":4,"doc_module_name":25,"category_name":120,"show_sort_weight":117,"slug":121},"World Cup","world-cup",{"id":123,"doc_module":4,"doc_module_name":25,"category_name":124,"show_sort_weight":123,"slug":125},10,"Lifestyle","lifestyle",{"id":127,"doc_module":4,"doc_module_name":25,"category_name":128,"show_sort_weight":96,"slug":129},19,"General","general",{"code":4,"msg":81,"data":131},{"doc_id":78,"user_id":132,"nickname":42,"user_avatar":11,"doc_module":4,"category_id":111,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":133,"file_id":134,"file_url":135,"file_type":136,"file_size":137,"view_count":26,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":138,"language":139,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":12,"update_tm":143,"read_time":144},8796093062539,"21.1 SCOPE.  \n21.1.1 Purpose. This section establishes drafting and dimensioning practices pertinent to the preparation of drawings for parts to be fabricated from sheet metal. Additional information is presented to assist the draftsman in establishing proper dimensions for certain features of formed sheet metal parts.  \n21.2 APPLICABLE DOCUMENTS. Note: DoD Policy Memo 05-3 “Elimination of Waivers to Cite Military Specifications and Standards in Solicitation and Contracts” has eliminated the need for waivers to use MIL-SPECS and MIL-STDS on DoD contracts. (See PREFACE 1, Section 2)  \nASME Y14 .100 Engineering Drawing Practices  \nMIL-STD-403 Preparation for and Installation of Rivets and Screws, Rocket & Missile Structure  \n(Inactive for New Design)  \nNAS 523 Fastener Code (Aerospace)  \nASME Y14 .5M Dimensioning and Tolerancing for Engineering Drawings  \n21.3 DEFINITIONS. (Alphabetically Listed) .  \n21.3.1 Bend Allowance. The length of the arc of the median line (neutral axis) of a bend between tangencies (from bend line to bend line) . See FIGURES 21-1 and 21-2.  \nSHEET METAL TERMS FIGURE 21-1  \nDRAWING REQUIREMENTS MANUAL 21-1  \n21.3.2 Bend Angle. The angle through which sheet metal is bent. It is measured from the flat through the bend to the finished angle after bending and is not to be confused with the included angle between the flange and adjacent leg. See FIGURE 21-2  \n21.3.3 Bend Line. The line of tangency where a bend changes to a flat surface or to a tangential bend with a different specified radius. There are two bend lines for each bend. See FIGURE 21-1.  \n21.3.4 Bend Radius. The radial value of a bend in sheet metal or similar material. The minimum bend radius is the smallest radius value that may be used to bend the material without cracking or requiring additional work when forming the flanges. See FIGURE 21-1 through 21-4.  \n21.3.5 Bend Relief. For optimum forming, interfering material at flange extremities is removed to a point behind the bend line to prevent cracking of the material when forming the flanges. See FIGURE 21-6 thru 21-8.  \n21.3.6 Bevel, Closed. The condition of a flange bent more than 90o from its flat condition. See FIGURE 21-2.  \n21.3.7 Bevel, Open. The condition of a flange bent less than 90o from its flat condition.  \n21.3.8 Blank. A flat sheet metal shape of approximately the correct size to make a finished part. The part is usually trimmed to size after forming.  \n21.3.9 Center Line Of Bend. A radial line from the center of the bend radius which bisects the included angle between bend lines. See FIGURE 21-3.  \n21.3.10 Developed Length. The length of a flat part or material which can be bent to make the part depicted on a drawing. This length is always shorter than the sum of mold line dimensions on the part. See FIGURE 21- 5.  \n21.3.11 Dimpling. Stretching a relatively small shallow indentation into sheet metal. Stretching metal into a conical flange for use of a countersunk rivet head or screw. Dimpling is stronger than countersinking and should be performed on thin panels.  \n21.3.12 Flat Pattern. A flat layout of a formed sheet metal part which can be bent to make the finished part without trimming after forming.  \n21.3.13 Form Block Line. The inside mold line of a part.  \n21.3.14 Joggle. An offset in the face of a part which has an adjacent flange. See FIGURE 21-9 and 21-10.  \n21.3.15 Mold Line. The line of intersection of two flat surfaces of a formed sheet metal part. The term alone usually refers to the outside mold line. See form block line also. See FIGURE 21-1.  \n21.3.16 Median Line (Neutral Axis.) In bent material, the median line (neutral axis) is a line of zero stress within the bend, thus it is not subjected to tension (stretched) or subjected to compression (compressed) . All material to the outside of the median line is in tension, and all material to the inside of the median line is in compression. The median line is located approximately 44% of the material thickness from ","cbCaitDAuqEa7emF","https://ap.wps.com/l/cbCaitDAuqEa7emF","pdf",978389,32,"English","# 21.1 Scope\n## 21.1.1 Purpose\n# 21.2 Applicable Documents\n# 21.3 Definitions\n## 21.3.1 Bend Allowance\n## 21.3.2 Bend Angle\n## 21.3.3 Bend Line\n## 21.3.4 Bend Radius\n## 21.3.5 Bend Relief\n## 21.3.6 Bevel, Closed\n## 21.3.7 Bevel, Open\n## 21.3.8 Blank\n## 21.3.9 Center Line Of Bend\n## 21.3.10 Developed Length\n## 21.3.11 Dimpling\n## 21.3.12 Flat Pattern\n## 21.3.13 Form Block Line\n## 21.3.14 Joggle\n## 21.3.15 Mold Line\n## 21.3.16 Median Line (Neutral Axis)\n## 21.3.17 Set Back\n## 21.3.18 Tool Holes Or Pin Holes\n# 21.4 General\n## 21.4.1 Fabrication Of Sheet Metal Parts\n# 21.5 Characteristics Of Sheet Metal Bends\n## 21.5.1 Location Of Median Line (Neutral Axis) For Bend Allowance Calculations","[{\"question\":\"What is the purpose of Section 21 (21.1.1)?\",\"answer\":\"It establishes drafting and dimensioning practices for preparing drawings for sheet-metal parts, helping draftsmen set proper dimensions for features of formed parts.\"},{\"question\":\"Which standards and documents are referenced as applicable (21.2)?\",\"answer\":\"The section cites ASME Y14.100 and ASME Y14.5M drawing practices, along with MIL-STD-403 for rivets and screws and NAS 523 fastener code for aerospace, plus a DoD policy memo affecting waiver requirements.\"},{\"question\":\"How is the median line (neutral axis) used in bend allowance calculations (21.5.1 and 21.3.16)?\",\"answer\":\"It represents the line within the bend where no stretching or compression occurs, and it is located approximately 44% of the material thickness from the inside surface of the bend; it forms the basis for bend allowance calculations.\"}]","DRM11thSECT21 | PDF",1792792722,81]